This R21 proposal describes a feasibility study targeted for funding under the Neurosciences Technology Development program (PA-98-050) through NICHD. The proposal outlines three aims necessary to develop functional magnetic resonance imaging (fMRI) technology as a tool for evaluation of pediatric candidates for cochlear implantation. FMRI is a relatively new and highly sophisticated technology, which can provide a window into the functional human brain. Cochlear implantation is also a cutting edge technology in approximately the same development phase as fMRI. The integration of these technologies presents a challenge. Successful integration of these technologies in very young children is a formidable proposition but offers the opportunity for new understanding of human deafness, cortical plasticity, brain development and connectivity. The proposal has three simple aims, which constitute the necessary preliminary steps toward development of fMRI technology for use in pediatric cochlear implant candidates. We aim to: 1) Determine whether auditory cortical activity can be observed with fMRI with sound stimulation in sedated toddlers and young children with normal hearing; 2) Demonstrate that auditory cortical activity can be observed with fMRI using sound stimulation in compliant older children with severe to profound, sensorineutral hearling loss; and 3) Perform fMRI of auditory stimulation in severely to profoundly hearing impaired toddlers and young children under sedation. These aims define a logical course toward establishing that fMRI can be used successfully in pediatric cochlear implant candidates, many of whom are very young. If this feasibility study is successful, it will provide essential data needed to develop the neuroscience technology required to apply functional neuroimaging in severely to profoundly hearing impared toddlers and young children. This project will also more clearly define the potential role of fMRI in the selection and management of cochlear implant patients. The most optimistic outcome of this project would be that fMRI could be used to predict future benefit from a cochlear implant in a child. Short of achieving this high goal, this project will certainly accomplish the stated purpose of the Neurosciences Technology Development program (PA-98-050) of supporting "research that will develop significant enhancements to existing technologies important to neuroscience and research that will translate a scientific concept into the basis for a future technology that may advance understanding of important neuroscience research problems."